button {
    outline: 3px dashed #f0f;
    /* or, just the colour */
    outline-color: #f0f;
}

button.search {
    outline: none;
    -moz-outline: none; /* Firefox 1.0 and earlier, if you care */
}

button::-moz-focus-inner { border: 0; }

onclick="this.blur();"